Sen. David Vitter wants members of Congress to disclose whether they’ve exempted their staffs from joining the Obamacare exchanges.

The Louisiana Republican is upset that lawmakers are being given discretion to decide which staffers will be pushed onto the District of Columbia’s health insurance exchange and which will be able to keep their current health insurance plans. He said that amounted to a “loophole.”

“For members to use this illegal loophole so that some staff stay off the exchanges altogether is outrageous,” Vitter said in a statement. “It flies in the face of the exact language of Obamacare.”

Vitter is putting all of his staff, including those who work for him on the Environment and Public Works Committee, on the exchanges.

Vitter also led an unsuccessful effort to ban the government from making health contributions for congressional staffers, lawmakers and political appointees who enter the exchanges.